N = int(input())
c = input()
Rn = c.count("R")
c2 = c[:Rn]
res = c2.count("W")
print(res) N = int(input()) N int(input()) int input() input c = input() c input() input Rn = c.count("R") Rn c.count("R") c.count c count "R" c2 = c[:Rn] c2 c[:Rn] c :Rn Rn res = c2.count("W") res c2.count("W") c2.count c2 count "W" print(res) print res Rn = c.count("R") c.count("R") Rn c2 = c[:Rn] c[:Rn] c2 res = c2.count("W") c2.count("W") res N = int(input()) int(input()) N c = input() input() c
N = int(input())
c = input()
Rn = c.count("R")
c2 = c[:Rn]
res = c2.count("W")
print(res)